How do I access resources on this web site programmatically?

## tool_example.pl ##
use strict;
use warnings;
use LWP::UserAgent;

my $base = 'http://www.uniprot.org';
my $tool = 'mapping';
my $params = {
  from => 'ACC', to => 'P_REFSEQ_AC', format => 'tab',
  query => 'P13368 P20806 Q9UM73 P97793 Q17192'
};

my $agent = LWP::UserAgent->new;
push @{$agent->requests_redirectable}, 'POST';
print STDERR "Submitting...\n";
my $response = $agent->post("$base/$tool/", $params);

while (my $wait = $response->header('Retry-After')) {
  print STDERR "Waiting ($wait)...\n";
  sleep $wait;
  print STDERR "Checking...\n";
  $response = $agent->get($response->base);
}

$response->is_success ?
  print $response->content :
  die 'Failed, got ' . $response->status_line . 
    ' for ' . $response->request->uri . "\n";

## tool_example.rb ##
require 'net/http'

base = 'www.uniprot.org'
tool = 'mapping'
params = { 
  'from' => 'ACC', 'to' => 'P_REFSEQ_AC', 'format' => 'tab',
  'query' => 'P13368 P20806 Q9UM73 P97793 Q17192'
}

http = Net::HTTP.new base
$stderr.puts "Submitting...\n";
response = http.request_post '/' + tool + '/', 
  params.keys.map {|key| key + '=' + params[key]}.join('&')

loc = nil
while response.code == '302'
  loc = response['Location']
  response = http.request_get loc
end

while loc
  wait = response['Retry-After'] or break
  $stderr.puts "Waiting (#{wait})...\n";
  sleep wait.to_i
  $stderr.puts "Checking...\n";
  response = http.request_get loc
end

response.value # raises http error if not 2xx
puts response.body

import java.util.logging.Logger;


public class ToolExample
{
  private static final String base = "http://www.uniprot.org";
  private static final Logger log = Logger.getAnonymousLogger();
  
  private static void run(String tool, NameValuePair[] params)
    throws Exception
  {
    HttpClient client = new HttpClient();
    String location = base + '/' + tool + '/';
    HttpMethod method = new PostMethod(location);
    ((PostMethod) method).addParameters(params);
    method.setFollowRedirects(false);
    log.info("Submitting...");
    int status = client.executeMethod(method);
    
    if (status == HttpStatus.SC_MOVED_TEMPORARILY)
    {
      location = method.getResponseHeader("Location").getValue();
      method.releaseConnection();
      method = new GetMethod(location);
      status = client.executeMethod(method);
    }
    
    while (true)
    {
      int wait = 0;
      Header header = method.getResponseHeader("Retry-After");
      if (header != null)
        wait = Integer.valueOf(header.getValue());
      if (wait == 0)
        break;
      log.info("Waiting (" + wait + ")...");
      Thread.sleep(wait * 1000);
      
      log.info("Checking...");
      method.releaseConnection();
      method = new GetMethod(location);
      status = client.executeMethod(method);
    }
    
    if (status == HttpStatus.SC_OK)
      System.out.println(method.getResponseBodyAsString());
    else
      log.severe("Failed, got " + method.getStatusLine() + " for " + method.getURI());
    
    method.releaseConnection();
  }
  
  public static void main(String[] args)
    throws Exception
  {
    run("mapping", new NameValuePair[] {
      new NameValuePair("from", "ACC"),
      new NameValuePair("to", "P_REFSEQ_AC"),
      new NameValuePair("format", "tab"),
      new NameValuePair("query", "P13368 P20806 Q9UM73 P97793 Q17192"),
    });
    
  }
}